Sharing Traffic 2G-3G • Load Base Handover 2G-3G • Cell Reselection 3G-2G 2G-3G • PUSH AMR
I insert classification level 1 © NSN Siemens Networks
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Load based Handover GSM -> WCDMA Load of GSM cell 100%
Load reason Handovers for speech
Speech Speechto toWCDMA WCDMA only with high only with highGSM GSMload load
More Morecapacity capacity for speech for speech
Packet PacketData Datato toWCDMA WCDMA regardless of GSM regardless of GSMload load
Higher Higherbit bitrates rates for data users for data users
80% Utran HoThScTpdc = 80%
Packet PacketBCCH BCCHparameters parameterscan canbe beused used totopush GPRS mobiles to WCDMA push GPRS mobiles to WCDMA
0% Soc Classification level 2 © NSN Siemens Networks
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Load & Coverage Reason Handover Load Loadreason reason Handover Handoverfor forspeech speech and for HSCSD and for HSCSD WCDMA low loaded
GSM high loaded
GSM GSM
GSM GSM WCDMA WCDMA
GSM GSM
GSM GSM WCDMA WCDMA
WCDMA WCDMA Load reason Handover
Soc Classification level 3 © NSN Siemens Networks
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WCDMA WCDMAcan canbe beused used to relieve GSM overload to relieve GSM overload GSM GSMcan canbe beused usedto toextend extend WCDMA WCDMAcoverage coveragearea area
GSM GSM
GSM GSM
Mobile moving
Coverage reason Handover
Load based Handover Process: GSM-> WCDMA Handover HandoverTriggering TriggeringThresholds Thresholdsset setininBSC BSC
Inter-RAT Inter-RATmeasurements measurementsstarts startsinincase case The RXLEV of the serving cell is above The RXLEV of the serving cell is aboveoror below belowthe thegiven giventhreshold thresholdQsearch_C Qsearch_C
Handover HandoverDecision Decisionisisdone doneinincase caseofof Load Loadofofthe theserving servingcell cell>>Load_Threshold Load_Threshold &&CPICH Ec/No> min Ec/No CPICH Ec/No> min Ec/NoThreshold Threshold
MS MSselects selectsthe thetarget targetUTRAN UTRANcell cellbased based on measurement results on measurement results Handover Handovercommand commandisissend sendtotoMSC MSC
Soc Classification level 4 Š NSN Siemens Networks
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Parameters are sent from the BSC to the mobile in the Measurement Information message MS is measuring the UTRAN cells continuously if they are defined as a neighbor , The number of GSM neighbor reported could be 3-6 depending on the set value of parameter FDD_MULTIRAT_REPORT (0,1,2=def,3).
The load is measured in the cell level by comparing the occupied TCHs to the available TCHs (20 s interval used) Load Threshold for Speech Calls or Transparent Data inter-RAT Handover: utranHoThScTpdc (Min Traffic Load TDHO), default = 80% minEcnoThreshold (Min CPICH EC/NO Threshold), default –15 dB
Hidden
Changeable
ISHO 2G -> 3G Parameters Parameter
Specification name
min traffic load for speech call
NSN parameter
Range
Default value
LOAD_THRESHOLD_FOR_S utranHoThScTpdc (LTSC) C_IS_HO
0-100%
80%
minimum CPICH Ec/Io level
MIN_ECNO_THRESHOLD
-24…0.5 dB
-15 dB
min interval between unsucc ISHO attempt
MIN_INTERVAL_BETWEEN_ minIntUnsuccIsHo (UMIU) UNSUCC_ISHO_ATTEMPT
0…255 s
3s
threshold for multi-RAT MS
Qsearch_C
0…15
15 (never) rec. 7 (always)
minEcnoThreshold (MET)
qSearchC (QSRC)
Specification name
Parameter explanation
FDD_REP_QUANT
Indicates the reporting quantity for UTRAN FDD 0=RSCP, cells 1=EC/NO
Not tunable, Fixed value 1
3G_SEARCH_PRIO
Indicates if 3G cells may be searched when BSIC decoding is required
Not tunable, Fixed value 1
FDD_MULTIRAT_REPORTING
The number of cells from the access 0…3 technology/mode FDD that shall be included in the measurement report
Not tunable, Fixed value 2
Qsearch_C_Initial
Indicates the Qsearch value to be used in 0 = use Qsearch_I, connected mode before Qsearch_C is received 1 = ∞ (always)
Not tunable, Fixed value 0
Soc Classification level 5 © NSN Siemens Networks
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Value range
0 = no, 1 = yes
Note
Handover Control • GSM ISHO • Load Based Handover to WCDMA • Cell Reselection
Soc Classification level 6 © NSN Siemens Networks
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Cell Reselection 3G -> 2G CPICH EcNo
UE starts GSM measurements if CPICH Ec/No < qQualMin + sSearchRAT
SintraSearch
First ranking of all the cells based on CPICH RSCP (WCDMA) and RSSI (GSM)
SinterSearch
Rs = CPICH RSCP + Qhyst1 Rn= Rxlev(n) - Qoffset1
SsearchRAT qQualMin No
Serving WCDMA cell calculation, with hysteresis parameter
Neighbour WCDMA or GSM cell calculation with offset parameter
Yes
Rn (GSM) > Rs (WCDMA) And Rxlev (GSM) >QrxlevMin Second ranking only for WCDMA cells based on CPICH Ec/No Rs = CPICH Ec/No + Qhyst2 Rn=CPICH_Ec/No(n)-Qoffset2 Soc Classification level 7 © NSN Siemens Networks
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Cell re-selection to GSM Cell re-selection to WCDMA cell of highest R value
Cell Reselection 3G -> 2G UE ranks the serving cell and the measured neighboring cells to find out if reselection should be made All the measured suitable cells (S-criteria) are included in the ranking. Criteria for a suitable cell (S-criteria) is defined as WCDMA intra-frequency neighbor cell: CPICH Ec/No > AdjsQqualmin and CPICH RSCP > AdjsQrexlevmin
WCDMA inter-frequency cell: CPICH Ec/No > AdjiQqualmin and CPICH RSCP > AdjiQrexlevmin
GSM cell: Rxlev > Qrxlevmin
Ranking is done using Criteria R, and the UE reselects to the cell with highest Rcriteria. R-criteria is defined as: For serving cell: Rs = Qmeas,s + Qhysts For neighboring cell Rn = Qmeas,n – Qoffsetts,n Qmeas is CPICH Ec/No for WCDMA cell and RxLev for GSM cell GSM measurements can start when CPICH Ec/Io of serving cell is below Ssearch_RAT + QqualMin Soc Classification level 8 © NSN Siemens Networks
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Cell Reselection 2G -> 3G Cell Reselection
List
BCCH: FDD_Qm in, FD
Qsearch_I: 0..15; 1; 7 (always)
D_Qoffset
GSM MS starts WCDMA measurements if : RLA_C< F(Qsearch_I) for 0<Qsearch_I<=7 or RLA_C> F(Qsearch_I) for 7<Qsearch_I<=15
check
no priorities between WCDMA neighbors
at least every 5 s
Measurement Updates: • RLC_C value of the serving cell • + least 6 strongest non serving GSM cells
If, for suitable UMTS cell & for a period of 5 s: CPICH RSCP > RLA_C + FDD_Qoffset
and CPICH Ec/No ≥ FDD_Qmin
Fdd_Qoffset: select always (value is -infinity)
WCDMA cell reselection FDD_Qmin:
-20... –6; 2; -12 dB Soc Classification level 9 © NSN Siemens Networks
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Cell Re-selection Parameters • Qsearch_I and Qsearch_P define the threshold for non-GPRS/GPRS (respectively) capable
UEs to measure 3G neighbour cells when a running average of the received downlink signal level (RLA_C) of the serving cell is below (0-7) or above (8-15) the threshold Value
0
1
…
6
7
dBm
-98
-94
…
-74
If RLA_C < -94 UE starts 3G measurements
8
Always -78
9
10
…
14
15
-74
-70
…
-54
Never
If RLA_C > -70 UE starts 3G measurements
UE always measures 3G cells
• FDD_Qoffset and FDD_GPRS_Offset the non-GPRS/GPRS (respectively) capable UEs
add this offset to the RLA_C of the GSM cells. After that the UE compares the measured RSCP values of 3G cells with signal levels of the GSM cells Value
0
1
2
3
…
8
…
14
15
dBm
-always
-28
-24
-20
…
0
…
24
28
Always select irrespective of Soc Classification level value 10RSCP © NSN Siemens Networks
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Reselect in case RSCP > GSM RXLev (RLA_C) +28dB
Cell Re-selection Example: weaker WCDMA Non GPRS case RSCP/ RLA_C
Idle IdleMode Mode
Ec/No
Cell re-selection to WCDMA
RLA_C
Serving GSM Cell
Qsearch_I = -98 dBm FDD_Qoffset = -8 dB
Measurements starts (serving cell)
Neighbour WCDMA Cell
FDD_Qmin=0 -12 dB
RSCP Ec/N0 Minimum Quality Requirement for WCDMA 5 sec.
CPICH RSCP > RLA_C + FDD_Qoffset &
CPICH Ec/No ≥ FDD_Qmin Soc Classification level 11 © NSN Siemens Networks
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GSM GSM -> -> WCDMA WCDMA
t
Cell Re-selection Example: stronger WCDMA GPRS case RSCP/ RLA_C
Connected ConnectedMode Mode
Ec/No
RLA_P Cell re-selection to WCDMA
FDD_GPRS_Qoffset = 8 dB Qsearch_P = -98 dBm
Serving GSM Cell (Best)
RSCP Measurements starts (serving cell) FDD_Qmin = -20 dB Neighbour WCDMA Cell
Ec/N0
Minimum Quality Requirement for WCDMA t 5 sec.
Soc Classification level 12 © NSN Siemens Networks
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GSM GSM -> -> WCDMA WCDMA
How to avoid ping pong ? • When phone is camped on 3G, GSM measurements can start when CPICH Ec/Io of serving cell is below Ssearch_RAT + QqualMin. • When phone is camped on GSM, cell reselection to 3G is possible if CPICH Ec/Io of the candidate is above FDD_Qmin. • Therefore, to avoid ping pongs between 3G and GSM the following condition should be met: FDD_Qmin >= QqualMin+Ssearch_RAT CPICH Ec/Io
FDD_Qmin >= -12 dB
QqualMin +Ssearch_RAT Ssearch_RAT=4 dB
QqualMin=-18 dB
Camping on 3G
Camping on GSM Camping on 3G t
Soc Classification level 13 © NSN Siemens Networks
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PUSH AMR • Push Voice 3G-2G
Soc Classification level 14 © NSN Siemens Networks
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Forced Handover for AMR Voice Call AMR voice call setup in 3G • Feature can be used to push 3G AMR calls to 2G • Extreme parameter setting for ISHO trigger cause “UE Tx power” (event 6A)
WCDMA forced handover to GSM
GSMcauseTxPWRUL
GSM
FMCG; 0 (no) / 1 (yes)
FMCG: GSMcauseTxPwrUL FMCG: GsmUETxPwrThrAMR
UE
[..]
RNC RRC: RadioBearerSetup
RRC: RadioBearerSetupComplete RRC: MeasurementControl RRC: MeasurementReport (event 6A)
UE immediately answers with Measurement Report „push“ means Handover, not Directed-Retry ! Soc Classification level 15 © NSN Siemens Networks
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ISHO measurements & HO to GSM
Remember:
6A: UE Tx power > absolute threshold max. allowed UE Tx Power (e.g. 21 dBm) + GsmUETxPwrThrAMR: FMCG; -60..0; 1; -3 dB here: - 60 dB !
Forced Handover for AMR Voice Call • FMCG: GSMcauseTxPwrUL • Range and step: 0 (False), 1 (True) • Indicates whether a handover to GSM caused by high UE TX power level is enabled. The handover is enabled when the value of the parameter is "Used“ • To enable feature, setting must be 1 (True)
• FMCG: GsmUETxPwrThrAMR • Range and step: -60..0 dB • This parameter determines the UE TX power threshold for a CS voice connection. If the handover to GSM caused by high UE TX power level is enabled, the RNC starts inter-RAT (GSM) measurements when the UE TX power reaches this threshold. The UE TX power threshold is relative to the maximum TX power level an UE can use on the DPCH in the cell (or the maximum RF output power capability of the UE, whichever is lower • To enable feature, setting must be –60 dB
Soc Classification level 16 © NSN Siemens Networks
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THANKS
Soc Classification level 17 © NSN Siemens Networks
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